Matthew D. Pepe, Bradford S. Tucker, and Carl Basamania
DEFINITION
Pectoralis major ruptures are injuries to the one of the largest and strongest muscles of the shoulder region.
Injuries can be divided into complete and partial tears.
Complete tears typically occur at the tendon-to-bone junction and involve both heads.
Partial tears can occur to either the sternocostal or the clavicular head.
Both types may also occur at the musculotendinous junction or the muscle itself.
ANATOMY
The pectoralis major is a broad triangular muscle that originates from the medial clavicle, anterior sternum, costal cartilages to the sixth rib, and external obliques.
It inserts into the proximal humerus on the lateral edge of the bicipital groove. It has two distinct heads: the smaller clavicular head and the larger sternocostal head.
The pectoralis major tendon is about 5 cm long. The insertion site has two distinct laminae. The clavicular head is anterior and distal and is about 1 cm long, and the sternocostal head inserts posterior and is 2.5 cm long.3
The sternocostal head spirals 180 degrees on itself, inserting posterior to the clavicular head, creating a rolled inferior surface that is the axillary fold (FIG 1).
The function of the pectoralis major varies depending on the division. Its primary function is to adduct the humerus and its secondary role is to forward flex and internally rotate. The clavicular head primarily forward flexes and horizontally adducts. The sternocostal head internally rotates and adducts.
PATHOGENESIS
Pectoralis major ruptures typically occur when a powerful eccentric or concentric forward flexion or adduction load to the humerus (such as heavy bench pressing) occurs. The final 30 degrees of humeral extension disproportionally stretches the inferior fibers of the sternocostal head, putting it at a mechanical disadvantage and predisposing it to injury. The inferior fibers fail first, followed by progression toward the clavicular head.
Ruptures may also occur when a traction injury such as rapid extension, abduction, or external rotation force is applied to the extremity (such as catching oneself during a fall).
Injuries to the muscle belly can also be caused by a direct blow, which can result in hematoma formation.
Patients often hear or feel a rip or tear in the shoulder region, feel a burning pain, and occasionally hear a pop.
Younger patients (under 30 years) tear at the tendon–bone insertion, whereas patients over 30 tend to tear at the musculotendinous junction.
Swelling and ecchymosis occur from several hours to days after the injury in the lateral chest wall, upper arm, or axilla.
Medial muscle retraction along with loss of the axillary fold may not be evident for several days until the swelling subsides.
Anabolic steroids weaken the muscle–tendon unit, making patients more susceptible to tears.1
NATURAL HISTORY
Weakness of the affected shoulder in adduction, forward flexion, and internal rotation can be expected with nonoperative treatment of full-thickness tears of both heads or of partial tears of the sternocostal head.
Isokinetic strength testing has demonstrated 25% to 50% deficits of strength in adduction and internal rotation in preoperative patients and people treated nonoperatively.3,4,9
Cosmetic deformity occurs secondary to the loss of the tendon in the axillary fold as well as from the medial retraction that occurs during contraction of the muscle.
Partial tears will elicit a variable degree of weakness and deformity, depending on the amount and location of tendon torn.
FIG 1 • A. Anatomy of the pectoralis major. Two distinct heads are clearly demonstrated. B. The clavicular portion of the tendon inserts anterior and distal. The sternocostal lamina inserts posterior and proximal.
The initial pain and cramping that occurs during contraction of the pectoralis major usually subsides in 2 to 3 months.
Patients treated nonoperatively for full-thickness tears will complain of weakness and fatigue with recreational and occupational activities as well as the cosmetic deformity.
PATIENT HISTORY AND PHYSICAL FINDINGS
A previous history of pain is not typical.
The patient’s occupation and involvement in sports and weight-lifting activities are important in decision making regarding treatment.
Physical examination initially will yield painful range of motion of the shoulder and arm. When the swelling subsides, patients typically have full range of motion of the glenohumeral joint.
Swelling and ecchymosis are variable depending on the chronicity and the degree of the tear.
Isometric or resisted adduction and forward flexion will show the loss of the tendon in the axillary fold and medial retraction of the pectoralis muscle.
The examiner should instruct the patient to hold the arm at 90 degrees of abduction, and the anterior head of the deltoid will be accentuated. If the arm is held in forward flexion, the clavicular head will be accentuated (FIG 2A).
Having patients press their hands together in front of their body for isometric adduction allows inspection of both sides at the same time and simultaneous palpation (FIG 2B).
Manual strength testing will demonstrate weakness in adduction and forward flexion.
FIG 2 • A. Resisted forward flexion demonstrates the intact clavicular head and the defect from the ruptured sternocostal head. The retracted sternocostal head is evident. B. Isometric adduction demonstrating the normal contour of the right pectoralis major compared with the medially retracted left sternocostal head.
IMAGING AND OTHER DIAGNOSTIC STUDIES
A standard shoulder radiographic series is obtained to rule out fractures, avulsions, or signs of instability.
An MRI of the chest, with attention to the pectoralis major tendon, may be obtained to evaluate the location of the tear or assist in making the diagnosis.6,11 It has been shown to be beneficial in differentiating musculotendinous junction ruptures from tendinous avulsions and may change the treatment strategy.11 It is difficult, however, to distinguish between complete and partial ruptures (FIG 3).
FIG 3 • Axial and coronal T2-weighted MRIs.
Ultrasound may be used to identify the location and severity of the tear. Results, however, are user-dependent.
DIFFERENTIAL DIAGNOSIS
Rotator cuff tears
Proximal biceps tear
Anterior shoulder instability
Deltoid rupture
Latissimus dorsi tear
Brachial plexus injury
NONOPERATIVE MANAGEMENT
Nonoperative treatment is indicated for medial tears, intramuscular tears, or tears at the musculotendinous junction in some people. Also, nonoperative treatment should be considered in low-demand patients with complete or partial distal tendon ruptures.
Nonoperative treatment begins with a sling for the first 7 to 10 days. Ice should be applied intermittently for the first 72 hours.
Gentle active assisted range of motion is then begun, avoiding aggressive external rotation, abduction, or extension stretching in the initial phases.
Strength training is typically initiated at 6 to 8 weeks. Depending on the level of occupational or sporting demands, patients may return between 8 and 12 weeks.
Strength deficits of 25% and 50% can be expected with nonoperative treatment.5
SURGICAL MANAGEMENT
Pectoralis major repair is recommended for all complete distal tears, partial distal tears in high-demand patients, and musculotendinous junction tears in high-demand patients with large defects.
A direct tendon-to-bone repair with heavy, nonabsorbable sutures is performed for complete distal tears and sternocostal tears.
A side-to-side repair is used for musculotendinous junction tears.
Preoperative Planning
A standard examination under anesthesia of the glenohumeral joint is performed to evaluate for instability.
Positioning
The patient is placed in the 30-degree modified beach chair position. The shoulder and arm are prepared free. A shoulder positioning device is helpful, but not necessary, to position the arm during surgery (FIG 4).
FIG 4 • Operative setup. The patient is placed in the beach chair position with the arm draped free.
Approach
An anterior approach to the shoulder and proximal humerus is used—the internervous plane between the axillary nerve of the deltoid and the superior and inferior pectoral nerves of the pectoralis major.
TECHNIQUES
PECTORALIS MAJOR REPAIR USING DRILL HOLES
Our preferred technique for direct primary repair of the pectoralis major tendon is to attach the tendon directly to the humeral cortex using drill holes.
A limited 4to 5-cm deltopectoral incision is made (TECH FIG 1A). The cephalic vein is identified and retracted laterally with the deltoid.
The biceps tendon is identified, gaining access to the insertion of the pectoralis major just lateral to the biceps tendon in the proximal humerus. In cases of musculotendinous junction tears or partial tears, the entire tendon or a portion of it will be intact.
Medial dissection is then performed to identify the retracted tendon. The sternocostal and clavicular heads are identified as well as the location of the tendon or musculotendinous junction tear.
In cases of complete tears, the tendon is typically retracted medially and folded upon itself, identifiable by palpation.
A traction suture is placed in the tendon, and stepwise gentle blunt mobilization of the muscle and tendon is performed.
The excursion of the tendon is then tested. Even in cases of chronic tears, the tendon can typically be mobilized to reach the humerus without difficulty.
The tendon edge is freshened with a scalpel. A no. 5 braided, nonabsorbable suture is used in a Bunnell or modified Mason-Allen locking stitch in the end of the tendon (TECH FIG 1B). Two or three sutures are used, spaced about 1 cm apart, depending on the width of the tendon.
TECH FIG 1 • Drill hole technique. A. Limited deltopectoral incision. B. Modified Mason-Allen stitch in tendon edge. C. Drill hole placement with 2-0 Vicryl sutures placed. (continued)
TECH FIG 1 • (continued) D. Bunnell technique with sutures passed and ready to tie. The central holes are shared by two sutures. E. Suture passage when modified Mason-Allen stitch is used. The deep suture is passed through the drill holes. F. Bunnell technique after suture tying.
The insertion site lateral to the biceps tendon is decorticated with a burr.
A commercially available drill can be used to drill the proximal and distal sets of holes. A bridge of 8 to 10 mm is adequate secondary to the thickness of the humerus.
The holes usually need to be overdrilled with a 2-mm drill bit, as the humeral cortex is extremely strong and thick.
A needle with a matching radius of curvature is then used to pass a 2-0 looped Vicryl passing suture (TECH FIG 1C). Each corresponding suture is passed using the 2-0 Vicryl passing suture.
The central drill holes are shared by the upper and lower respective sutures in a horizontal mattress configuration for the Bunnell technique (TECH FIG 1D).
If a modified Mason-Allen stitch was used, the deep suture is passed through the drill hole and the knot tied on the upper surface of the tendon (TECH FIG 1E).
The sutures are then tied with the arm in adduction and internal rotation to ensure apposition of the tendon to the humerus (TECH FIG 1F).
Alternatively, the drill holes may be made freehand and the sutures passed with either a free needle or a loop of 24-gauge wire.
PECTORALIS MAJOR REPAIR USING SUTURE ANCHORS
The musculotendinous unit is mobilized in the same way as described for drill hole repair. The humeral cortex is decorticated with a burr.
Two or three suture anchors are then placed in the humeral insertion, spaced 1 cm apart. The sutures are passed in a Kessler mattress stitch through the distal pectoralis tendon (TECH FIG 2).
One limb is passed in a simple fashion. This is used as the post during tying so the knot slides and apposes the tendon to the humerus without the knot lying in the repair site.
Metallic anchors loaded with braided, nonabsorbable no. 5 sutures are used, as the humeral cortex in this region may be too thick to accept an absorbable anchor.
TECH FIG 2 • Suture anchor technique: placement of sutures and passage through the tendon edge.
MUSCULOTENDINOUS JUNCTION REPAIRS
Multiple figure 8 or modified Kessler sutures of a no. 2 braided, nonabsorbable suture are used on both the superficial and deep layers.
The quality of the repair depends on the strength and the amount of tendon left on the muscular side.
PEARLS AND PITFALLS
POSTOPERATIVE CARE
The arm is kept in a sling for 6 weeks postoperatively. It is removed from the sling one or two times daily for gentle, progressive passive and active assisted range of motion of the shoulder, elbow, wrist, and hand.
The extremes of abduction and external rotation are avoided for the first 6 weeks. At this time, the sling is removed and unrestricted movement is allowed. In addition, strengthening is begun.
Return to full activities is generally achieved between 3 and 5 months.
OUTCOMES
There are no large prospective or randomized studies in the literature comparing operative and nonoperative treatment. Results are universally good with acute repairs (within 8 weeks).
Park and Espiniella7 in 1970 evaluated 30 patients with pectoralis major ruptures. The results were 90% good to excellent results with operative repair versus 75% with nonoperative treatment.
McEntire and colleagues5 in 1972 compared operative and nonoperative treatment in 11 patients. Again, operative repair had a more favorable outcome at 88% versus 83%, with a higher ratio of excellent to good results.
Zenman and coworkers10 in 1979 reviewed nine athletes with pectoralis major ruptures. Four patients were treated with surgical repair and had excellent results. All five of the patients treated nonoperatively had residual weakness, and two were dissatisfied with their outcome.
Kretzler and Richardson3 in 1989 reported on their results after repair of 16 distal tendon tears. Eighty-one percent regained full motion and strength. Two repairs that occurred 5 years after the injury had persistent weakness.
Wolfe and colleagues9 in 1992 evaluated 14 patients with pectoralis major ruptures, half of whom were treated with operative repair. Cybex strength testing demonstrated normal strength in the repaired patients, with persistent weakness in the unrepaired group.
Jones and Matthews2 in 1988 reviewed the literature and concluded that acute repair within 7 days has 57% excellent and 30% good results. Repair in the setting of a chronic tear yielded 0% excellent and 60% good results. They concluded that although chronic repair is possible even up to 5 years after the injury, the outcome is not as good as an acute repair, with a high likelihood of persistent weakness and cosmetic deformity.
Schepsis and colleagues8 in 2000 found that operatively repaired patients (both acute and chronic) had significantly better outcomes than conservatively treated patients.
There are no studies to date documenting rerupture after repair.
COMPLICATIONS
Complications are relatively infrequent after pectoralis major repair. One patient experienced loss of abduction.3 Another patient had ulnar-sided hand paresthesias of unknown etiology that spontaneously resolved.8
There have been several reports of complications in the elderly after rupture and nonsurgical management. One patient needed a blood transfusion. Two died of sepsis from an infected hematoma. Myositis ossificans developed in one patient 4 months after rupture.
REFERENCES
· Hunter MB, Shybut GT, Nuber G. The effect of anabolic steroid hormones on the mechanical properties of tendons and ligaments. Trans Orthop Res Soc 1986;11:240.
· Jones MW, Matthews JP. Rupture of the pectoralis major in weightlifters: a case report and review of the literature. Injury 1988; 19:219.
· Kretzler HH, Richardson AB. Rupture of the pectoralis major muscle. Am J Sports Med 1989;17:453.
· Liu J, Wu J, Chang S, Chou Y, et al. Avulsion of the pectoralis major tendon. Am J Sports Med 1992;20:366–368.
· McEntire JE, Hess WE, Coleman SS. Rupture of the pectoralis major muscle: a report of eleven injuries and review of fifty-six. J Bone Joint Surg Am 1972;54A:1040–1046.
· Miller MD, Johnson DL, Fu FH, et al. Rupture of the pectoralis major muscle in a collegiate football player: use of magnetic resonance imaging in early diagnosis. Am J Sports Med 1993;21: 475–477.
· Park JY, Espiniella LJ. Rupture of the pectoralis major muscle: a case report and review of the literature. J Bone Joint Surg Am 1970; 52A:577.
· Schepsis AA, Grafe MW, Jones HP, et al. Rupture of the pectoralis major muscle: outcome after repair of acute and chronic injuries. Am J Sports Med 2000;28:9–15.
· Wolfe SW, Wickiewicz TL, Cavanaugh JT. Ruptures of the pectoralis major muscle: an anatomic and clinical analysis. Am J Sports Med 1992;20:587.
· Zenman SC, Rosenfeld RT, Liscomb PR. Tears of the pectoralis major muscle. Am J Sports Med 1979;7:343.
· Zvijac JE, Schurhoff MR, Hechtman KS, et al. Pectoralis major tears: correlation of magnetic resonance imaging and treatment strategies. Am J Sports Med 2006;34:289–294.